Double-acting rotary piston pump



A. F. ENEMARK DOUBLE-ACTING ROTARY PISTON PUMP 7 Dec. 8, 1959 2Sheets-Sheet 1 Filed Jan. 2, 1957 Dec. 8, 1959 A. F.-ENEMARK 2,915,974

DOUBLE-ACTING ROTARY PISTON PUMP Filed Jan. 2, 1957 2 Sheets-Sheet 2United States Patent Ofii ce 2,9l5,%? i- Patented Dec. 8, 1959DOUBLE-ACTING ROTARY PISTON PUMP Arne Fromm Euemark, Sonderborg,Denmark, assignor to Danfoss ved ingenior Mads Clausen, Elsmark, Nordborg, Denmark, a Danish firm Application January 2, 1957, Serial No.632,142

Claims priority, application Denmark July 28, 1956 4 Claims. (Cl.103-'5) The invention relates to a double-acting rotary piston pump,preferably for feeding fuel to oil burners and of the kind in which arotatable, cylindrical body with a plurality of pump cylinders disposedwith their axes parallel to the axis of rotation of the pump has pistonsto which a reciprocating movement is imparted thereby that their endparts, located outside one end surface of the cylindrical body, underthe action of springs .rest in contact with a flat guiding surface. Thesaid guiding surface is obliquely disposed in relation to the axis ofrotation and is formed in a guiding disc which constitutes the endbottom of the pump casing, sliding members being furthermore provided tocooperate with the cylindrical body for controlling the flow of fuelfedto and discharged from the pump cylinders.

Double-acting piston pumps of the aforesaid kind are known andpreferably used in connection with low pressure oil burners in whichapportionment of a regulable quantity of fuel fed to the oil burner isrequired. However, the quantity apportioned will be somewhat dependenton the pressure at which the oil is fed to the pump, and it is thereforecommon practice to insert a suction pump between the measuring pumpproper and the oil storage tank of the burner installation. The saidsuction pump is capable of counteracting the pressure drops involved bythe different levels of the measuring pump and the tank and by theresistance to the flow in their connecting pipings. These pressure dropsvary from one installation to another and with the operating conditionsof the burner and the diiferent quantities available in the tank. Thesaid suction pump is adapted to feed the measuring pump with excessiveamounts of oil and an overflow valve inserted in the pipe connecting thesuction pump and the measuring pump is adapted to control that themeasuring pump is fed with oil at a constant pressure determined by theadjustment of the overflow valve. The suction pump may be a pump of anykind whatever and be mechani-.

cally coupled in various manner to the motor shaft of the oil burnerwhich shaft as a rule also drives the fan of the oil burner.

It is the object of the invention to devise the construction of adouble-acting rotary piston pump of the aforesaid kind, in which thesuction pump and the measuring pump are built together to form a verysimple unit that is suitable for mass production and particularly owingto its comparatively simple composition is both durable and reliable inoperation, in addition to being adjustable in a very convenient manner.

An essential feature of a double-acting rotary piston pump according tothe invention is that a plurality of the pump cylinders are adapted tocooperate as a suction pump, whereas another set of cylinders is adaptedto operate as a measuring pump, inserted in parallel or in series withthe suction pump. The sliding members,-

of the pump, the said sliding disc being provided with at least two setsof arc-shaped sliding grooves recessed in such surface of the slide discas faces the body, each of the said grooves extending over to an angularare adapted to the number of cylinders and being adapted to cooperatewith the inlet and discharge openings of the pump cylinders and with thefeed and discharge pipings of the two pumps.

As a result, a simple and compact pump construction is obtained in whichthe pumping effect of the suction pump and the measuring pump alike maybe regulated by turning the guiding disc and the sliding disc inrelation to each other and in which the sealing between the slidingmembers and the cylindrical body is obtained solely by axial attachmentof the sliding disc in relation to the cylindrical body. Any wear on thesurfaces sliding against each other will thereby be automaticallyequalized, and waste of oil and intake of air owing to such wear, whichmay be injurious to the pump operation, may be avoided.

In one embodiment of the piston pump according to the invention one setof pump cylinders is designed with a relatively large diameter and theother set of pump cylinders with a relatively small diameter.

As a result, the suction pump pumps for each revolution a larger amountof fuel than the measuring pump, and by coupling the suction pump to themeasuring pump in a manner known per se by means of a piping which isprovided with an overflow valve it will always be possible to feed thefuel to the measuring pump at a pressure predetermined by the adjustmentof the overflow valve.

In a preferred embodiment of the piston pump according to the inventionan axial plane of symmetry of the sliding grooves of the suction pumplying between the ends of the two grooves is staggered by an angle of 60in relation to the corresponding plane of symmetry of the slidinggrooves of the measuring pump.

As a result, the pumping effect of the measuring pump can be variedalmost linearly from nil to a relative high value by turning the planeof symmetry of the guiding disc in relation to a plane of symmetry ofthe sliding disc simultaneously with the pumping eifect of the suctionpump only varying comparatively little. This quality in the piston pumpaccording to the invention may advantageously be used for regulating thefuel supply in oil burners or similar installations where regulablequantities of liquid or gaseous substances are to be apportioned.

The invention will now be further described with reference to thedrawing, in which- Figure 1 is a perspective view, partially in section,of essential-parts in an embodiment of a double-acting rotary pistonpump according to the invention,

Figure 2 is a section of same on the line -II-II of Figure 1,

Figure 3 is a section of same on the line IIIII-I of Figure 2, and

v Figure 4 is a curve showing the variation of the pumping effect ofsame when essential parts of the pump are turned in relation to eachother.

In the drawing 1 denotes a rotatable cylindrical body which is coupledto the driving shaft 2 of an oil burner and is provided with a pluralityof pump cylinders 3, 4 mounted with their axes parallel to therotational axis of the pump so that the axes are angularly staggered,for example in one and the same cylindrical surface coaxial with therotational axis. A set of the pump cylinders 3 is adapted to cooperateas a suction pump, being provided with cylindrical pistons 5 which underthe action of springs 6 rest with their end parts 8 that are lyingoutside the one end surface 7 of the cylindrical body 1 against 3 a fiatguiding surface 9 which is obliquely disposed in relation to the axis ofrotation, the said guiding surface 9 being formed on a guiding disc 10which in combination with a ring 11 constitutes an end plate of the pumpca sing 12. Another set of pump cylinders 4 is adapted to cooperate as ameasuring pump of preferably less pumping effect than the suctionpumpwhich is constituted by the pump cylinders 3, and each of the cylinders4 are provided with pistons 13 which under the action of springs 14 restwith their end sections 15 against the guiding surface 9. At the otherend surface 16 of the cylindrical body and in close contact with thesaid end surface is provided a sliding disc 17, positioned about thedriving shaft 2 of the pump and permanently secured in the pump casing12. The said sliding disc has a set of arc-shaped sliding grooves 18, 19recessed in the end surface of the sliding disc 17 which faces the body1, concentrically with the rotational shaft of the pump. The slidinggrooves 18, 19 cooperate with the inlet and outlet openings 20 of thepump cylinders 3. The sliding disc 17 is furthermore provided withanother set of arc-shaped sliding grooves 21, 22 which are likewisearranged concentrically with the rotational shaft of the pump andcooperate with the inlet and outlet openings 23 of the measuring pumpcylinders 4. The sliding grooves 18, 19, corresponding to the inlet andoutlet openings 20 of the suction pump cylinders 3, are in theembodiment according to the invention shown in the drawing located atgreater distance of the rotational axis than the sliding grooves 21, 22corresponding to the inlet and outlet openings 23 of the measuring pumpcylinders 4, the last mentioned openings communicating with the slidinggrooves 21, 22 by radial passages 24 from the bottom of the measuringpump cylinders 4 to the end surface 16. In the sliding disc 17 there isrecessed a radial feeding passage 25, emanating from the slidinggroove-18, which passage is in passage 30 of the measuring pump the oilwill by means of suction be passed from the sliding groove 21 to the'sliding groove 22 and further'to'the discharge passage 31 of themeasuring pump and hence through the discharge piping 32 to the burnerof the oilfiring installation.

It is known that a piston pump of the aforesaid kind yields its maximumpumping effect when the plane A of symmetry of the guiding surface 9 iscoinciding with the plane of symmetry extending between the two. slidinggrooves, that is, for the suction'pump incorporated in the pump a slidesymmetry plane B and for the measuring pump incorporated in the pump aslide symmetry plane B as indicated in Figure 3. The pumping effect willdecrease in accordance with a cosine curve when the two planes ofsymmetry, A and B or A and B respectively, form an angle or, and thepumping effect will be equal to nil when the angle on is equal to i90 asshown in Figure 4.

In a preferred embodiment of the piston pump according to the inventionan axial plane of symmetry B lying inidways between the sliding grooves18, 19 of the suction pump are staggered by an angle B=60 in relation tothe corresponding plane of symmetry B of the sliding grooves 21, 22of-the measuring pump. The pumping effect of the suction pump can beregulated as its maximum value, located at the maximum of the cosinecurve,

by turning the plane .of symmetry A of the guiding disc in relation tothe plane of symmetry B for the sliding grooves of the suction pump, forexample up to 'an angle a =30 or oc =+30, from the position in which thepumping effect is optimum and where the plane A coincides withthe planeB whereby the pumpdirect communication with a suction chamber 27 whichis in series with the feed piping 26 for the pump as shown in Figure 2,and correspondingly a discharge passage 28, extending in the pump casing12 from the sliding groove 19 may lead to the return piping 29 of theoil burner or to a return chamber (not shown), which communicates withthe return piping. I

The suction chamber 27 of the pump or the return chamber (not shown) isconnected to a feeding passage 30 which opens into the sliding groove 21for the measuring pump cylinders 4, and similarly a radial dischargepassage 31 leads from the sliding groove 22 and opens into the surfaceof the sliding disc 17 facing the opposite direction of the cylindricalbody 1, the said discharge passage 31 communicating with the dischargepiping 32 of the' measuring pump cylinders. The said piping 32 which isindicated by broken lines in Figure 3 leads to the burner nozzle (notshown) of the oil burner.

It will be appreciated from the above that during the rotation ofthe'pump the suction pump will draw oil from the pump feed piping 26 orfrom the suction chamber 27 ing effect of the suction pump will varybetween 87%, corresponding to a=i30 and cos u=0.866 to 100%,corresponding to =0 and cos x=1.000. At the same time the pumping effectof the measuring pump will, owing to the angular staggering applied,i.e. B=60%, at a corresponding turning of the plane A vary from.()%

through the feeding passage 25 when the cylindrical body 1 rotates, forexample in the direction indicated by an arrow 33 in Figure 3, inrelation to the stationary sliding disc 17 in the pump casing 12 and theguiding disc 10, i.e. from the position indicated by the dotted circle20 in Figure 3 to the diametrically opposed position. During the sameinterval the piston 5 will under the action of the spring 6 move fromits innermost position in the cylinder 3 as shown in the drawing to itsoutermost position, the end part 8 of the piston 5, remaining in contactwith the guiding surface 9. During the remaining part of its movementthe piston 5 will force the oil in the cylinder'3 through the dischargeopening 20 and the sliding groove 19'and the discharge passage 28 to thereturn piping 29 onto the returnchamber, which may communicate with thefeeding passage 38 of the sliding 'groove2l Any excessive amount of oilwill via the return piping 29 be returned to the oil storage tank. Fromthe feeding corresponding to 04:90" and cos 01:0, to 87%, correspondingto a=30 and cos a=0.866, as will be seen from Figure 4. The pumpingeffect of the measuring pump will thus vary approximated linearly from0% to 87% when the plane of symmetry 8 of the guiding disc is turned :30in relation to the plane of symmetry B of the sliding grooves 18, 19,whilethe pumping effect of the suction pump simultaneously withapproximation will keep constant, varying only between 87% and'l00%.

Although the invention is described in the foregoing in an embodimentusing four cylinders, it will be appreciated that by modifications thatwill be obvious to one skilled' in the art the invention may be usedboth for other numbers of cylinders and for an irregular number ofcylinders in the two sets.

What I'claim and desire to secure by Letters Patent is:

l. A double-acting rotary piston fluid feed pump having fluid inletmeans and fluid outlet means and comprising, in combination, a rotatablecylindrical body formed with a plurality of cylinders disposed withtheir axes parallel to the axis of rotation of said body including afirst pair of cylinders and a second pair of cylinders, said body havinga forward end face and a rearward end face and said cylinderscommunicating with said end faces, resiliently urged pistons disposed insaid cylinders, said pistons having their forward ends projecting beyondsaid forward end face of said body, means defining a fiat guidingsurface disposed opposite said forward end face of said body and engagedby said forward ends of said pistons, saidguiding surface beingobliquely disposed with respect to the axis of rotation of said body, asliding member disposed opposite said rearward end face of saidrotatable cylindrical body, said sliding 'P 'Q id d with at least twopairs of arc shaped sliding grooves recessed in such first face of thedisc, one of said pairs of grooves being positioned to communicate withsaid first pair of cylinders and the other pair of grooves beingpositioned communicate with said second pair of cylinders, and saidinlet means and said outlet means communicating respectively with onemember of each pair of grooves, one pair of grooves being staggered byan angle of 60 in relation to the second pair of grooves.

2. A double-acting rotary piston fluid feed pump having fluid inletmeans and fluid outlet means and comprising, in combination, a rotatablecylindrical body formed with a plurality of cylinders disposed withtheir axes parallel to the axis of rotation of said body including afirst pair of cylinders and a second pair of cylinders, said first pairhaving a greater diameter than said second pair and said cylinders beingdisposed along a circle coaxial with the axis of rotation in such mannerthat cylinders of different diameters alternate along circumference ofsaid circle, said body having a forward end face and a rearward end faceand said cylinders communicating with said end faces, resiliently urgedpistons disposed in said cylinders, said pistons having their forwardends projecting beyond said forward end face of said body, meansdefining a flat guiding surface disposed opposite said forward end faceof said body and engaged by said forward ends of said pistons, saidguiding surface being obliquely disposed with respect to the axis ofrotation of said body, a sliding member disposed opposite said rearwardend face of said rotatable cylindrical body, said sliding member havingthe form of a disc having a first face applied tightly to said rearwardend surface of the cylindrical body but non-rotatable therewith, saiddisc being provided with at least two pairs of arc-shaped slidinggrooves recessed in such first face of the disc, one of said pairs ofgrooves being positioned to communicate with said first pair ofcylinders and the other pair of grooves being positioned to communicatewith said second pair of cylinders, and said inlet means and said outletmeans communicating respectively with one member of each pair ofgrooves, one pair of grooves being staggered by an angle of 60 inrelation to the second pair of grooves.

3. A double-acting rotary piston fluid feed pump having fluid inletmeans and fluid outlet means and comprising, in combination, a rotatablecylindrical body formed with a plurality of cylinders disposed withtheir axes parallel to the axis of rotation of said body including afirst pair of cylinders and a second pair of cylinders, said body havinga forward end face and a rearward end face and said cylinderscommunicating with said end faces, resiliently urged pistons disposed insaid cylinders, said pistons having their forward ends projecting beyondsaid forward end face of said body, means defining a flat guidingsurface disposed opposite said forward end face of said body and engagedby said forwards ends of said pistons, said guiding surface beingobliquely disposed with respect to the axis of rotation of said body, asliding member disposed opposite said rearward end face of saidrotatable cylindrical body, said sliding member having the form of adisc having a first face applied tightly to said rearward end surface ofthe cylindrical body but non-rotatable therewith, said disc beingprovided with at least two pairs of arc-shaped sliding grooves recessedin such first face of the disc, one of said pairs of grooves beingpositioned to communicate with said first pair of cylinders and beingradially outwardly spaced in relation to the other pair of grooves, andthe other pair of grooves being positioned to communicate with saidsecond pair of cylinders, and said inlet means and said outlet meanscommunicating respectively with one member of each pair of grooves, onepair of grooves being staggered by an angle of in relation to the secondpair of grooves.

4. A double-acting rotary piston fluid feed pump having fluid inletmeans and fluid outlet means and comprising, in combination, a rotatablecylindrical body formed with a plurality of cylinders disposed withtheir axes parallel to the axis of rotation of said body including afirst pair of cylinders and a second pair of cylinders, said first pairhaving a greater diameter than said second pair and said cylinders beingdisposed along a circle coaxial with the axis of rotation in such mannerthat cylinders of difierent diameters alternate along circumference ofsaid circle, said body having a forward end face and a rearward end faceand said cylinders communicating with said end faces, resiliently urgedpistons disposed in said cylinders, said pistons having their forwardends projecting beyond said forward end face of said body, meansdefining a fiat guiding surface disposed opposite said forward end faceof said body and engaged by said forward ends of said pistons, saidguiding surface being obliquely disposed with respect to the axis ofrotation of said body, a sliding member disposed opposite said rearwardend face of said rotatable cylindrical body, said sliding member havingthe form of a disc having a first face applied tightly to said rearwardend surface of the cylindrical body but non-rotatable therewith, saiddisc being provided with at least two pairs of arc-shaped slidinggrooves recessed in such first face of the disc, one of said pairs ofgrooves being positioned to communicate with said first pair ofcylinders and being radially outwardly spaced in relation to the otherpair of grooves, and the other pair of grooves being positioned tocommunicate with said second pair of cylinders, and said inlet means andsaid outlet means communicating respectively with one member of eachpair of grooves, one pair of grooves being staggered by an angle of 60in relation to the second pair of grooves.

References Cited in the file of this patent UNITED STATES PATENTS1,506,892 Egersdorfer Sept. 2, 1924 1,714,148 Weldy May 21, 19292,445,281 Rystrom July 13, 1948

